package day33;

import java.util.Scanner;

/**
 * @author tongchen
 * @create 2023-04-11 19:43
 */
public class Main1 {
    public static void main(String[] args) {
        Scanner scanner=new Scanner(System.in);
        while(scanner.hasNext()){
            int from=scanner.nextInt();
            int to=scanner.nextInt();
            //创建81个数组
            int[]nums=new int[81];
            nums[1]=1;
            nums[2]=1;
            for(int i=3;i<=to;++i){
                nums[i]=nums[i-1]+nums[i-2];
            }
            int sum=0;
            for(int i=from;i<=to;++i){
                sum+=nums[i];
            }
            System.out.println(sum);
        }
    }

}
